Field of the Invention
The present invention relates to an image processing device to improve visual recognition of a radiation image, and particularly relates to the image processing device that can provide an image having high visual recognition despite incorporating an image of a metal piece into the radiation image.*
Technical Background
A medical facility equips the radiation device to obtain the subject's image using radiation. Such radiographic device comprises the image processing device to display an image having high visual recognition on the monitor by the addition of an image processing on the original image.
Some of the image processing devices can generate a tomographic image. According to such image processing device, when a plurality of original images that are continuously taken while changing the imaging direction are input, the original images are superimposed so as to output the tomographic image. A tomographic image is an image incorporating the image appearing when the subject is cross-sectionally imaged at a plan thereof.
Meantime, in the case of the subject who took a surgery to build up the bone with a metal piece in the past, an image of the metal piece is incorporated into the imaged original image. When the subject having the implanted metal piece inside body is imaged, the hardly radiation-transmissive metal piece is obviously incorporated into the original image. The metal piece on the original image appears as an extremely bright image on the original image.
The image processing device cannot generate the tomographic image having superior visual recognition by just simply superimposing the images incorporating the metal piece. Because a false image in the periphery of the metal piece incorporated into the generated tomographic image takes place. Then, according to the conventional image processing device, the tomographic image is generated by performing a separate image processing on the metal piece of the original image and other regions so as to prevent an occurrence of the false image in the tomographic image (e.g., see Patent Document 1, the entire contents of which are incorporated herein by reference).
A map capable of showing distribution of the metal piece in the original image is required so as to execute an image processing capable of reducing such false image. According to the conventional constitution, such map can be generated by executing a binarization processing on the original image. Provided the binarization processing is executed on the original image, an image as if in which an extremely dark metal piece incorporated into the original image is extracted can be obtained. The Otsu method can be applied to determine the threshold value relative to the binarization processing.